Dynamic Characteristic Analysis Method And Improvement Design Of Dc High Power Contactor Considering Collision Bounce

At present,with the emergence of a number of new energy prod ucts such as wind power and photovoltaic power generation and the development of a series of military and civilian electrical appliances such as all-electric appliances and allelectric aircraft,the demand for high-power contactor is increasing with each passing day,and higher requirements for its contact performance and electrical life are also required.The dynamic characteristics of the contactor considering collision bounce as an important indicator to evaluate its performance,has become a hot and difficult issue in current research.Due to the large number of mechanical parts in the contactor,there are collisional contact phenomena between components during its switching process.The instantaneous and nonlinearity of the impact collision problem makes the movement state of the structural system more complicated.The issue in the current researches is mostly simplified,however,the dynamic characteristics of structural system under different contact forms are different and a further study of its dynamic characteristic is needed.Therefore,properly dealing with the collision contact problem in the closing process is the key to study the dynamic characteristics of the contactor.Moreover,the short time arc caused by collision bounce is the main reason of welding and bonding,which directly affects the performance and service life of the contactor.In order to meet the performance requirements of high-power contactors for national defense,military and society,it is very necessary to establish a multi-physics dynamic theoretical model and calculation method considering collision bounce.In order to suppress the collision bounce of the contactor structure,the relevant researches on the multi-physics modeling,calculation method,test device,influence factor analysis and improved design are carried out in this study,respectively.Firstly,a dynamic electromagnetic model considering the effects of eddy current and inductance effect is established.the interaction of eddy current and inductance effects with the contactor's motion state and electromagnetic force can be evaluated.Taking the collision contact in the dynamic process of the contactor as the breakthrough point,the contactor's linear motion and nonlinear collision motion model are established.Considering the effects of temperature and repeated short-time work on the magnetization characteristic and coil resistance of the contactor,a finite element model of the thermal field for the electromagnetic structure is established,and a model of contactor machine,electric magnetic and thermal modeling,which considers the collision bouncing,is finally built.After that,the multi-physics coupled calculation method of dynamic characteristic for the contactor is proposed to realize the dynamic and con tinuous loading of the current,electromagnetic force and reaction force,which lays the foundation for the data call in multi-field calculation.At the same time,when the movable part moves in the compressible air,the automatic mesh technology is used to redistribute the compressible part and control the fixed part and the moving part of the mesh unit remaining unchanged and the electromagnetic parameters are solved in the time domain.Based on the concept of time coordination,It can be calculated the coupling electromagnetic properties,the dynamic characteristics including collision bounce and thermal behaviors of the contactor.On the basis of the coupling calculation method,the influence factors of the bouncing characteristics for the contactor are analyzed,and it was studied in detail about the effects of seven factors such as the overtravel spring pre-pressure,coil excitation voltage,contact distance,return spring pre-pressure,movable component and its additional mass,temperature and long time repeated short-time work on the contact bounce characteristics of contactor during dynamic process.Then,the contact bouncing simulation test device was designed,which realizes the test and analysis of contact bounce and obtains the relationship betwe en the time and displacement of the moving contact.The test device is an analog mechanical structure,which realizing the interchangeability of parts and obtaining the collision force between contact parts and load-carrying design.It has advantages of strong versatility,high precision,loadable test,real time display,and storage of test data.Finally,with the aim of suppressing the collision bounce of contactor,the orthogonal test design method is applied to design the parameters affecting the contactor's collision bounce,and the optimal parameter matching between the influencing factors of collision bounce is obtained.The simulation data are verified by experiments and compared with the results before the improved design.The results show that the bouncing of the improved design contactor is weakened,and it can meet the requirements of the suction and reverse force of the contactor.The problem studied in this research is the common problem of DC high-power contactors,and the conclusions can be directly applied to the dynamic characteristic calculation and optimization design process of new energy appliances,military and civilian appliances.